Iceberg Melting Research Articles

Direct link between iceberg melt and diatom productivity demonstrated in Mid-Pliocene Amundsen Sea interglacial sediments

Direct link between iceberg melt and diatom productivity demonstrated in Mid-Pliocene Amundsen Sea interglacial sediments

A finite volume formulation for one-dimensional Stefan problems

This paper presents a numerical formulation that combines the finite-volume method with a time-dependent boundary-fitted coordinate system to tackle the moving boundary problems for the one-dimensional (1-D) heat equation. Following the formulation process, an algorithm was created with the help of the linear algebra package Eigen to generate the data for the numerical solution. Four benchmark cases of heat conduction were investigated by this approach and compared to the analytical solution: a fixed boundary case, the liquid phase of a melting process, the solid phase of a melting process, and an ablating process. The results demonstrate the capability of the presented numerical formulation in efficiently solving the general 1-D heat problems, especially the one-phase Stefan problems, as well as the consistency of the numerical and analytical solutions. Future works can strive to extend the formulations to Stefan problems of two phases or higher dimensions. The work can then be extended to real-life applications, such as the spacecraft re-entry ablation process, and the process of iceberg melting, demonstrating its critical value in solving practical problems.

Tracking ablation and movement of icebergs with time-lapse photography at an alpine proglacial lake in Austria

ABSTRACT Little is known about the evolution and dynamics of icebergs in alpine lakes. We analyzed the movement and ablation patterns of icebergs at an ice-contact lake at Pasterze Glacier, Austria, using time-lapse images. Iceberg evolution was quantified for two timescales and related to meteorological as well as glacier ablation data from the adjacent glacier tongue. On a multiyear scale, ablation and movement of one iceberg (IB1) was monitored during a twenty-five-month period. On a single-day scale, the movement paths of eighty-four icebergs were tracked over 16 hours. Results for IB1 revealed an average iceberg ablation of 72 mm d−1 from June to September and no winter ablation. Iceberg ablation rates rose over time, explained by a rising surface area-to-volume ratio. Monitoring lake-wide iceberg movement for one day shows that a persistent katabatic glacier wind and a valley wind are the main influences on horizontal iceberg movement. Iceberg velocity is roughly 0.6 percent of the wind velocity. The existence of a wind-driven current on the lake surface is proposed. Sudden changes in movement rates, which are not explained by wind data, suggest that iceberg grounding is common. This study provides insight into iceberg melt rates in the absence of wave erosion.

Ice-shelf freshwater triggers for the Filchner–Ronne Ice Shelf melt tipping point in a global ocean–sea-ice model

Abstract. Some ocean modeling studies have identified a potential tipping point from a low to a high basal melt regime beneath the Filchner–Ronne Ice Shelf (FRIS), Antarctica, with significant implications for subsequent Antarctic ice sheet mass loss. To date, investigation of the climate drivers and impacts of this possible event have been limited because ice-shelf cavities and ice-shelf melting are only now starting to be included in global climate models. Using a global ocean–sea-ice configuration of the Energy Exascale Earth System Model (E3SM) that represents both ocean circulations and melting within ice-shelf cavities, we explore freshwater triggers (iceberg melt and ice-shelf basal melt) of a transition to a high-melt regime at FRIS in a low-resolution (30 km in the Southern Ocean) global ocean–sea-ice model. We find that a realistic spatial distribution of iceberg melt fluxes is necessary to prevent the FRIS melt regime change from unrealistically occurring under historical-reanalysis-based atmospheric forcing. Further, improvement of the default parameterization for mesoscale eddy mixing significantly reduces a large regional fresh bias and weak Antarctic Slope Front structure, both of which precondition the model to melt regime change. Using two different stable model configurations, we explore the sensitivity of FRIS melt regime change to regional ice-sheet freshwater fluxes. Through a series of sensitivity experiments prescribing incrementally increasing melt rates from the smaller, neighboring ice shelves in the eastern Weddell Sea, we demonstrate the potential for an ice-shelf melt “domino effect” should the upstream ice shelves experience increased melt rates. The experiments also reveal that modest ice-shelf melt biases in a model, especially at coarse ocean resolution where narrow continental shelf dynamics are not well resolved, can lead to an unrealistic melt regime change at downstream ice shelves. Thus, we find that remote connections between melt fluxes at different ice shelves are sensitive to baseline model conditions. Our results highlight both the potential and the peril of simulating prognostic Antarctic ice-shelf melt rates in a low-resolution global model.

Extracting iceberg freeboard using shadow length in high-resolution optical images

ABSTRACT Icebergs are big chunks of ice floating on the ocean surface, and melting of icebergs contributes for the major part of freshwater flux into ocean. Dynamic monitoring of the icebergs in Antarctica and accurate estimation of their volume are important for predicting the trend of freshwater budget of the Southern Ocean. The iceberg freeboard is a key parameter for measuring the thickness and volume of an iceberg and is defined as the difference between the elevation of iceberg surface and sea level. So far, freeboards of icebergs have been successfully extracted using InSAR DEM, and the laser and radar altimeter. However, uncertainties exist in these results mainly caused by missed detection of small icebergs due to the spatially sparse and temporally incomplete data coverage. In addition to the above techniques, optical images can also be used to extract the iceberg freeboard based on its geometric relationship with shadow length, which can effectively compensate for the above shortcomings. Although the feasibility has been preliminarily presented, the precision and extensive application of shadow-height method deserves further research, such as estimating the basal melting of icebergs. In this work, we tested an optical image-based freeboard extraction method over icebergs in Prydz Bay, Antarctica. A normalized shadow pixel index (NSPI) is designed to identify iceberg shadows with different shapes in HY-1C/D CZI and Sentinel-2 MSI optical images. The iceberg freeboard can be determined with an acceptable precision (2 m) in optical images compared with laser altimeter (i.e. ICESat-2) measurements. Moreover, basal melting of icebergs has been assessed according to the variation of freeboard using repeated optical observations. The results indicate that icebergs in the study area were with a mean freeboard of about 56 m in early December 2022, and experienced a decrease in freeboard of 1.9 m within two months, in correspondence with the Antarctic seasonal trend. The methodological framework, therefore, turns out to be a reliable complementary approach to studying the iceberg freeboard in polar regions.

Sea Ice‐Driven Iceberg Drift in Baffin Bay

AbstractBaffin Bay is the travel destination of most icebergs calving from west Greenland. They commonly follow the bay's cyclonic circulation and might end up far south along the coast of Newfoundland and Labrador, where many shipping routes converge. Given the hazard that icebergs pose to marine transportation, understanding their distribution is fundamental. One of the forces driving iceberg drift arises from the presence of sea ice. Observations in the Southern Ocean indicate that icebergs get locked in thick and concentrated sea ice. We present observations that support the occurrence of this sea ice locking mechanism (SIL) in Baffin Bay as well. Most iceberg models, however, represent the sea ice force over an iceberg as a simple drag force. Here, we implement a new parameterization in the iceberg module of the Nucleus for European Modeling of the Ocean (NEMO‐ICB) to represent SIL. We show that, by using this new parameterization, icebergs are more likely to travel outside of the Baffin Island Current during winter, which is supported by satellite observations. There is a slight improvement in the representation of iceberg severity along the coast of Newfoundland and Labrador and a slight shift of iceberg melt toward this region and Lancaster Sound/Hudson Strait. Although the impacts of icebergs on sea ice are still not represented, and targeted observations are needed for model calibration regarding sea ice concentration thresholds from which icebergs get locked, we are confident that this model improvement takes iceberg modeling one step forward toward reality.

A comprehensive Earth system model (AWI-ESM2.1) with interactive icebergs: effects on surface and deep-ocean characteristics

Abstract. The explicit representation of cryospheric components in Earth system models has become more and more important over the last years. However, there are few advanced coupled Earth system models that employ interactive icebergs, and most iceberg model studies focus on iceberg trajectories or ocean surface conditions. Here, we present multi-centennial simulations with a fully coupled Earth system model including interactive icebergs to assess the effects of heat and freshwater fluxes by iceberg melting on deep-ocean characteristics. The icebergs are modeled as Lagrangian point particles and exchange heat and freshwater fluxes with the ocean. They are seeded in the Southern Ocean, following a realistic present-day size distribution. Total calving fluxes and the locations of discharge are derived from an ice sheet model output which allows for implementation in coupled climate–ice sheet models. The simulations show a cooling of up to 0.2 K of deep-ocean water masses in all ocean basins that propagates from the southern high latitudes northward. We also find enhanced deep-water formation in the continental shelf area of the Ross Sea, a process commonly underestimated by current climate models. The vertical stratification is weakened by enhanced sea ice formation and duration due to the cooling effect of iceberg melting, leading to a 10 % reduction of the buoyancy frequency in the Ross Sea. The deep-water formation in this region is increased by up to 10 %. By assessing the effects of heat and freshwater fluxes individually, we find latent heat flux to be the main driver of these water mass changes. The altered freshwater distribution by freshwater fluxes and synergetic effects play only a minor role. Our results emphasize the importance of realistically representing both heat and freshwater fluxes in the high southern latitudes.

Laboratory experiments of melting ice in warm salt-stratified environments

Melting icebergs provide nearly half of the total freshwater flux from ice shelves to the ocean, but the availability of accurate, data-constrained melting rate parametrisations limits the correct representation of this process in ocean models. Here, we investigate the melting of a vertical ice face in a warm, salt-stratified environment in a laboratory setting. Observations of the depth-dependent melting rates ${m}$ and boundary layer flow speed $U$ are reported for a range of initially uniform far-field ambient temperatures $T_a$ above ${10}\,^{\circ }{\rm C}$ . Ice scallops are characteristic features observed in all experiments, with the width of the scallops consistent with the theory of double-diffusive layers. The morphology of the scallops changes from symmetric about the scallop centre in the colder experiments to asymmetric in the warmer experiments. Observed melting rates are consistent with a melting rate scaling of the form ${m}\propto U\,\Delta T_a$ proposed by previous work in less extreme parameter regimes, where $\Delta T_a$ is the magnitude of thermal driving between the ambient and ice–fluid interface. Our results indicate that ice scalloping is closely linked to the naturally convecting flow of the ambient fluid. Depth-averaged melting rates depend on the buoyancy frequency in the ambient fluid, and double-diffusive convection promotes a turbulent-flux regime distinct from that explained previously in an unstratified regime. These findings have implications for parametrising melting rates of icebergs and glaciers in numerical models or potential freshwater harvesting operations, and provide insights into the interplay between stratification and ice melting.

Fjord circulation induced by melting icebergs

Abstract. In an iceberg-choked fjord, meltwater can drive circulation. Down-fjord of the ice, buoyancy and rotation lead to an outflowing surface coastal current hugging one side of the fjord with an inflowing counter-current below. To predict the structure and evolution of these currents, we develop an analytical model – complemented by numerical simulations – that involves a rectangular fjord initially at rest. Specifically, we (i) start with the so-called Rossby adjustment problem; (ii) reconfigure it for a closed channel with stratification; and (iii) generalize the conventional “dam-break” scenario to a gradual-release one that mimics the continual, slow injection of meltwater. Implicit in this description is the result that circulation is mediated by internal Kelvin waves. The analytical model shows that if the total meltwater flux increases (e.g., a larger mélange, warmer water, or enhanced ice–ocean turbulence) then circulation strength increases as would be expected. For realistic parameters, a given meltwater flux induces an exchange flow that is ∼50 times larger. This factor decreases with increasing water column stratification and vice versa. Overall, this paper is a step toward making Greenland-wide predictions of fjord inflows and outflows induced by icebergs.

Laboratory Investigations of Iceberg Melting under Wave Conditions in Sea Water

Changes in the masses of icebergs due to deterioration processes affect the drift of icebergs and should be taken into account when assessing iceberg risks in the areas of offshore development. In 2022 and 2023, eight laboratory experiments were carried out in the wave tank of the University Centre in Svalbard to study the melting of icebergs in sea water under calm and rough conditions. In the experiments, the water temperatures varied from 0 ℃ to 2.2 ℃. Cylindrical iceberg models were made from columnar ice cores with a diameter of 24 cm. In one experiment, the iceberg model was protected on the sides with plastic fencing to investigate the iceberg’s protection from melting when towed to deliver fresh water. The iceberg masses, water temperatures, and ice temperatures were measured in the experiments. The water velocity near the iceberg models was measured with an acoustic Doppler velocimeter. During the experiments, time-lapse cameras were used to describe the shapes and measure the vertical dimensions of the icebergs. Using experimental data, we calculated the horizontal dimensions of icebergs, latent heat fluxes, conductive heat fluxes inside the iceberg models, and turbulent heat fluxes in water as a function of time. We discovered the influence of surface waves and water mixing on the melt rates and found a significant reduction in the melt rates due to the lateral protection of the iceberg model using a plastic barrier. Based on the experimental data obtained, the ratio of the rates of lateral and bottom melting of the icebergs and lateral melting of the icebergs under wave conditions was parametrized depending on the wave frequency.

Shape effect on solid melting in flowing liquid

Iceberg melting is a critical factor for climate change. However, the shape of an iceberg is an often neglected aspect of its melting process. Our study investigates the influence of different ice shapes and ambient flow velocities on melt rates by conducting direct numerical simulations of a simplified system of bluff body flow. Our study focuses on the ellipsoidal shape, with the aspect ratio as the control parameter. We found the shape plays a crucial role in the melting process, resulting in significant variations in the melt rate between different shapes. Without flow, the optimal shape for a minimal melt rate is the disk (two-dimensional) or sphere (three-dimensional), due to the minimal surface area. However, as the ambient flow velocity increases, the optimal shape changes with the aspect ratio. We find that ice with an elliptical shape (when the long axis is aligned with the flow direction) can melt up to 10 % slower than a circular shape when exposed to flowing water. Following the approach considered by Huang et al. (J. Fluid Mech., vol. 765, 2015, R3) for dissolving bodies, we provide a quantitative theoretical explanation for this optimal shape, based on the combined contributions from both surface-area effects and convective-heat-transfer effects. Our findings provide insight into the interplay between phase transitions and ambient flows, contributing to our understanding of the iceberg melting process and highlighting the need to consider the aspect-ratio effect in estimates of iceberg melt rates.

Carbon Dioxides Capture by Metal-Organic Frameworks Membranes and the Mixed-Matrix Membranes

The growing concern over carbon dioxide emissions has garnered substantial attention globally, as the relentless progression of technology continues to contribute to an increase in the production of this greenhouse gas. Consequently, the capture of carbon dioxide has emerged as a crucial mission to counteract the deleterious influences of climate change, which is exacerbated by the rising temperature across the world. This may also lead to various natural hazards, such as the melting of icebergs and the subsequent rise in sea levels. To address these issues, there is no denying the importance of the carbon dioxide capture process. This article will explore some of the methods of capturing carbon dioxide, including the utilization of metal-organic frameworks membranes and Mixed-Matrix Membranes, encompassing the design of such membranes and the strategies employed for their synthesis. To elucidate these techniques, the article will illustrate their processes through multiple examples and empirical findings, accompanied by relevant data.

A Study on the Improvement of Residential Environment by Climate Change

The effects of climate change are now appearing in many directions around the world. These climate change effects are related to changes in global climate patterns. Rising global temperatures are increasing the rate of melting of glaciers and icebergs, and accelerating sea level rise.
 Among them, climate change is closely related to the residential environment, which has various effects on the residential environment. The increase in energy consumption due to urbanization, the need for eco-friendly energy, and the importance of eco-friendly construction emphasize the relationship with the residential environment. This paper presents strategies and policies for adapting to the residential environment to adapt to climate change, and considers important adaptation strategies for increasing energy efficiency, utilizing renewable energy, improving urban planning, disaster management, and strengthening housing security. Proper response to climate change is essential to establish a sustainable and safe residential environment.
 Based on these findings, policies and strategies necessary to respond to climate change and create a sustainable residential environment can be prepared, and it is expected to contribute to reducing the vulnerability of the residential environment and improving the residential environment due to climate change.

Antarctic iceberg melt rate variability and sensitivity to ocean thermal forcing

AbstractChanges in iceberg calving fluxes and oceanographic conditions around Antarctica have likely influenced the spatial and temporal distribution of iceberg fresh water fluxes to the surrounding ocean basins. However, Antarctic iceberg melt rate estimates have been limited to very large icebergs in the open ocean. Here we use a remote-sensing approach to estimate iceberg melt rates from 2011 to 2022 for 15 study sites around Antarctica. Melt rates generally increase with iceberg draft and follow large-scale variations in ocean temperature: maximum melt rates for the western peninsula, western ice sheet, eastern ice sheet and eastern peninsula are ~50, ~40, ~5 and ~5 m a−1, respectively. Iceberg melt sensitivity to thermal forcing varies widely, with a best-estimate increase in melting of ~24 m a−1°C−1and range from near-zero to ~100 m a−1°C−1. Variations in water shear likely contribute to the apparent spread in thermal forcing sensitivity across sites. Although the sensitivity of iceberg melt rates to water shear prevents the use of melt rates as a proxy to infer coastal water mass temperature variability, additional coastal iceberg melt observations will likely improve models of Southern Ocean fresh water fluxes and have potential for subglacial discharge plume mapping.

Dissolution-driven propulsion of floating solids

We show that unconstrained asymmetric dissolving solids floating in a fluid can move rectilinearly as a result of attached density currents which occur along their inclined surfaces. Solids in the form of boats composed of centimeter-scale sugar and salt slabs attached to a buoy are observed to move rapidly in water with speeds up to 5 mm/s determined by the inclination angle and orientation of the dissolving surfaces. While symmetric boats drift slowly, asymmetric boats are observed to accelerate rapidly along a line before reaching a terminal velocity when their drag matches the thrust generated by dissolution. By visualizing the flow around the body, we show that the boat velocity is always directed opposite to the horizontal component of the density current. We derive the thrust acting on the body from its measured kinematics and show that the propulsion mechanism is consistent with the unbalanced momentum generated by the attached density current. We obtain an analytical formula for the body speed depending on geometry and material properties and show that it captures the observed trends reasonably. Our analysis shows that the gravity current sets the scale of the body speed consistent with our observations, and we estimate that speeds can grow slowly as the cube root of the length of the inclined dissolving surface. The dynamics of dissolving solids demonstrated here applies equally well to solids undergoing phase change and may enhance the drift of melting icebergs, besides unraveling a primal strategy by which to achieve locomotion in active matter.

Quantifying dissolution rates of Antarctic icebergs in open water

Abstract At any one time 130 000 icebergs are afloat in the Southern Ocean; 97% of these are too small to be registered in current satellite-based databases, yet the melting of these small icebergs provides a major input to the Southern Ocean. We use a unique set of visual size observations of 53 000 icebergs in the South Atlantic Ocean, the SCAR International Iceberg Database, to derive average iceberg dissolution rates. Fracture into two parts is the dominant dissolution process for tabular icebergs, with an average half-life of 30 days for icebergs <4 km length and 60 days for larger icebergs. Complete shatter producing many icebergs <1 km length is rare. A side attrition rate of 0.23 m d−1 combined with drift speed of 6 km d−1, or any proportional change in both numbers fits the observed changes in iceberg distribution. The largest injection into the Southern Ocean of fresh water and any iceberg-transported material takes place in a ~2.3 × 10⁶ km2 zone extending east-northeast from the Antarctic Peninsula to the Greenwich meridian. The iceberg contribution to salinities and temperatures, with maximum contribution north of the Weddell Sea, differs in some regions, from those indicated by tracking large icebergs.

Sedimentation on the Siberian Arctic Shelf as an indicator of the arctic hydrological cycle

Siberia occupies a significant part of the Eurasian continent and environmental changes in this region can have an important impact on the climate system of the Northern Hemisphere. The sediment flux of Siberian rivers is sensitive to changes in physical, chemical, and biological processes taking place on the continent, and these changes can be recorded in marine sediments on the Siberian Arctic Shelf. This paper presents data on grain-size distribution of the sediments, the sedimentation rates, and the mass accumulation rates on the shelf over the past 100 years. Age models are based on the decay rate of excess lead isotope 210Pb, taking into account the sorption capacity of the marine sediments, and the presence of cesium isotope 137Cs peaks in the sediment cores. The highest sedimentation and mass accumulation rates were observed prior to the 1920–40 and coincide with larger particle sizes, indicate a period of active sediment-laden sea ice and iceberg melt. Systematic decrease in the sedimentation and mass accumulation rates against the background of an increase in the proportion of silt fractions in the shelf sediments in the second half of the 20th century can be explained by an acceleration of the arctic hydrological cycle.

Impact of icebergs on the seasonal submarine melt of Sermeq Kujalleq

Abstract. The role of icebergs in narrow fjords hosting marine-terminating glaciers in Greenland is poorly understood, even though iceberg melt results in a substantial freshwater flux that can exceed the subglacial discharge. Furthermore, the melting of deep-keeled icebergs modifies the vertical stratification of the fjord and, as such, can impact ice–ocean exchanges at the glacier front. We model an idealised representation of the high-silled Ilulissat Icefjord in West Greenland with the MITgcm ocean circulation model, using the IceBerg package to study the effect of submarine iceberg melt on fjord water properties over a runoff season, and compare our results with available observations from 2014. We find the subglacial discharge plume to be the primary driver of the seasonality of circulation, glacier melt and iceberg melt. Furthermore, we find that melting of icebergs modifies the fjord in three main ways: first, icebergs cool and freshen the water column over their vertical extent; second, iceberg-melt-induced changes to fjord stratification cause the neutral buoyancy depth of the plume and the export of glacially modified waters to be deeper; third, icebergs modify the deep basin, below their vertical extent, by driving mixing of the glacially modified waters with the deep-basin waters and by modifying the incoming ambient waters. Through the combination of cooling and causing the subglacial-discharge-driven plume to equilibrate deeper, icebergs suppress glacier melting in the upper layer, resulting in undercutting of the glacier front. Finally, we postulate that the impact of submarine iceberg melt on the neutral buoyancy depth of the plume is a key mechanism linking the presence of an iceberg mélange with the glacier front, without needing to invoke mechanical effects.

Harold the Iceberg Melts Down by Lisa Wyzlic

Reviewed by: Harold the Iceberg Melts Down by Lisa Wyzlic Kate Quealy-Gainer, Editor Wyzlic, Lisa Harold the Iceberg Melts Down; illus. by Rebecca Syracuse. Feiwel, 2023 [40p] Trade ed. ISBN 9781250830623 $18.99 Reviewed from digital galleys R 6-8 yrs Harold already tends toward anxiety, so it doesn’t help when he watches a documentary about climate change and the melting icebergs—he is, after all, a head of iceberg lettuce, and now he’s quite certain he, too, will melt. None of his ideas to stop his supposed warming work out: the way to the freezer is blocked, the back of the fridge is sticky and gross, and the sunglasses and fake mustache are really just the last-ditch effort of a now panicking Harold. His friends finally get him to calm down with some breathing exercises, but the fact remains that the icebergs are melting, even if Harold is not—he can’t let his nerves get the best of him if he’s going to come up with a real plan to help his “cousins.” Wyzlic tackles eco-anxiety at a kid-friendly level, and cartoony Harold and his fridge friends soften the reality of a crisis that even younger readers are beginning to realize as dire. Despite Harold’s misread on his own danger in the iceberg situation, the book doesn’t mock or downplay his anxiety, but it does emphasize that worrying to the state of paralysis isn’t going to do anyone any good: “Harold was so focused on his impending doom that they couldn’t get through to him.” The breathing exercises seem a little trite in the face of the actual crisis, but there’s very much a “keep calm and carry [End Page 169] on” message here that, when paired with the real actionable items provided at the end of the book, gives some amount of agency to the generation that will be most impacted by the changing climate. Copyright © 2022 The Board of Trustees of the University of Illinois

Air Impurities Affecting the Melting of Icebergs and the Possibility of Airborne Microplastics Influence on Icebergs

The glaciers and icebergs are important not only for the hydrology but also the ecosystem of earth. The melting of glaciers will release the stored organic carbon and further accelerate the melting rate, thus affecting the global climate. Previous explorations have demonstrated that an important factor in the glacier retreat is human emissions. Carbon particles are major components, which could further be divided in to two categories by existing forms: light-absorbing aerosols (LAAs) and light-absorbing impurities (LAIs). Nowadays, microplastic particles (MP) have been discovered as a new form of pollutants in the environment. By comparing and analyzing the data of radiative forcing (RF) as well as optical characteristics, MPs have a great potential to accelerate the melting of glaciers and an impact on the ecosystem. Therefore, further research on the MPs are necessary to be completed.